"Comets that take more than 200 years to make one revolution around the Sun are notoriously difficult to study. Because they spend most of their time far from our area of the solar system, many "long-period comets" will never approach the Sun in a person's lifetime. In fact, those that travel inward from the Oort Cloud -- a group of icy bodies beginning roughly 186 billion miles (300 billion kilometers) away from the Sun -- can have periods of thousands or even millions of years.

NASA's WISE spacecraft, scanning the entire sky at infrared wavelengths, has delivered new insights about these distant wanderers. Scientists found that there are about seven times more long-period comets measuring at least 0.6 miles (1 kilometer) across than had been predicted previously. They also found that long-period comets are on average up to twice as large as "Jupiter family comets," whose orbits are shaped by Jupiter's gravity and have periods of less than 20 years.

Researchers also observed that in eight months, three to five times as many long-period comets passed by the Sun than had been predicted. The findings are published in the Astronomical Journal.

"The number of comets speaks to the amount of material left over from the solar system's formation," said James Bauer, lead author of the study and now a research professor at the University of Maryland, College Park. "We now know that there are more relatively large chunks of ancient material coming from the Oort Cloud than we thought."

The Oort Cloud is too distant to be seen by current telescopes, but is thought to be a spherical distribution of small icy bodies at the outermost edge of the solar system. The density of comets within it is low, so the odds of comets colliding within it are rare. Long-period comets that WISE observed probably got kicked out of the Oort Cloud millions of years ago. The observations were carried out during the spacecraft's primary mission before it was renamed NEOWISE and reactivated to target near-Earth objects (NEOs).

"Our study is a rare look at objects perturbed out of the Oort Cloud," said Amy Mainzer, study co-author based at NASA's Jet Propulsion Laboratory, Pasadena, California, and principal investigator of the NEOWISE mission. "They are the most pristine examples of what the solar system was like when it formed."

Astronomers already had broader estimates of how many long-period and Jupiter family comets are in our solar system, but had no good way of measuring the sizes of long-period comets. That is because a comet has a "coma," a cloud of gas and dust that appears hazy in images and obscures the cometary nucleus. But by using the WISE data showing the infrared glow of this coma, scientists were able to "subtract" the coma from the overall comet and estimate the nucleus sizes of these comets. The data came from 2010 WISE observations of 95 Jupiter family comets and 56 long-period comets.

The results reinforce the idea that comets that pass by the Sun more often tend to be smaller than those spending much more time away from the Sun. That is because Jupiter family comets get more heat exposure, which causes volatile substances like water to sublimate and drag away other material from the comet's surface as well.

The existence of so many more long-period comets than predicted suggests that more of them have likely impacted planets, delivering icy materials from the outer reaches of the solar system.

Researchers also found clustering in the orbits of the long-period comets they studied, suggesting there could have been larger bodies that broke apart to form these groups.

The results will be important for assessing the likelihood of comets impacting our solar system's planets, including Earth.

"Comets travel much faster than asteroids, and some of them are very big," Mainzer said. "Studies like this will help us define what kind of hazard long-period comets may pose."

NASA's Jet Propulsion Laboratory in Pasadena, California, managed and operated WISE for NASA's Science Mission Directorate in Washington. The NEOWISE project is funded by the Near Earth Object Observation Program, now part of NASA's Planetary Defense Coordination Office. The spacecraft was put into hibernation mode in 2011 after twice scanned the entire sky, thereby completing its main objectives. In September 2013, WISE was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify potentially hazardous near-Earth objects."

We need to get NEOcam launched before 2022,tiompan.Your petty nonsense is petty nonsense.Write nasty notes to the folks at Cahokia to your heart's content.

Usually people believe what they want to believe until reality intrudes.

Ya know EP... That's really interesting info.But I somehow can't grasp why you would archive your NEO/Impacter stuff here, on this board. It is almost not even tangentially relevant to the subject of archaeology. We have more or less agreed that impacts may have entered into the archaeological record through ancient folklore & oral histories... But do you have to bore the shit out of us with your cockeyed theories? SHEESH!!! Give it a rest, will ya?

circumspice wrote:But I somehow can't grasp why you would archive your NEO/Impacter stuff here, on this board. It is almost not even tangentially relevant to the subject of archaeology. We have more or less agreed that impacts may have entered into the archaeological record through ancient folklore & oral histories... But do you have to bore the shit out of us with your cockeyed theories? SHEESH!!! Give it a rest, will ya?

Agree ,although folklore/oral histories / ethnography have their limited uses in archaeology , large amounts of salt are required .E.P. The petty nonsense is your inability to face up to you errors .

circumspice wrote:Ya know EP... That's really interesting info.But I somehow can't grasp why you would archive your NEO/Impacter stuff here, on this board. It is almost not even tangentially relevant to the subject of archaeology. We have more or less agreed that impacts may have entered into the archaeological record through ancient folklore & oral histories... But do you have to bore the shit out of us with your cockeyed theories? SHEESH!!! Give it a rest, will ya?

Hi spice -

Asteroid and comet impacts are a new major environmental factor in human societies globally.It also appears that they are key to many ancient human magical practices,and are very key to archaeology, and human evolution and behaviors.

There is a reason why God is in heaven, instead of under the earth, or in the water.There was a reason for the Maya heart sacrifice,and for other Meso-American magical practices.

NASA's original impact estimate was based solely on lunar data,and is now known to be far wrong.This is now being corrected for larger impact events by geological research on Earth.

The only way of getting data for smaller impact events is by looking for archaeological discontinuities,and proto-historical records.

This is where archaeology comes in.Right now the discussion concerns a discussion of rituals practiced at Gobekli Tepe.In general the discussiono concerns whether Comet Encke wax responsible for the Holocene Start Impact Events,or whether it was Comet Giacobini Zinner or another different comet.

This is why the increase in the observable population of comets is relevant.We need to rigorouly nail this all downto get NEOcan operational by 2022.

Usually people believe what they want to believe until reality intrudes.

circumspice wrote:But I somehow can't grasp why you would archive your NEO/Impacter stuff here, on this board. It is almost not even tangentially relevant to the subject of archaeology. We have more or less agreed that impacts may have entered into the archaeological record through ancient folklore & oral histories... But do you have to bore the shit out of us with your cockeyed theories? SHEESH!!! Give it a rest, will ya?

Agree ,although folklore/oral histories / ethnography have their limited uses in archaeology , large amounts of salt are required .E.P. The petty nonsense is your inability to face up to your errors .

tiompan, when I make mistakes I do my best to correct them immediately.IN this regard I'd also like to note that the wonderful thing about footnotesis that they allow you to blame your mistakes on someone else.

Since you have an issue with the American usage of the word "henge",I invite you to write as many nasty notes to the folks at Cahokia as your heart desires.

Usually people believe what they want to believe until reality intrudes.

Best from you just isn't good enough EP. There is no American usage of "henge" there is the right and wrong usage ,and of course the one you made up . The fantasy one happens to be wrong. But is it not the only error you continually evade .Remember this one " the people on Malta disappear from the face of the Earth the same year as the Rio Cuarto impacts, 2,360 BCE." or "

Then "“the alignments were to Comet Giacobini Zimmer. “ you got the name of the comet there is no evidence that it would have been seen in the period , the direction of supposed alignment was 180 degrees out , you confused the the comet with the Draconids and there was nothing to support the contention of an "alignment in the first place . The clincher" “Collins has been trying to find a reason for Gobleki Tepe's alignment to celestial north.The reason for that is straight forward:that is where Comet Giacobini Zimmer approached the Earth from: “ No it didn't , you made that up too . " Thom's hypothesis about the henges is now established doctrine" . Another fantasy , you were asked to provide evidence for what Thom's hypothesis might be , but failed to do so . Hardly surprising it doesn't exist .

And then there is a huge amount of nonsense about GT and KT that you just evade discussing .

Give us break ,stop wasting time and space .

How about some info on the Yuchi monuments that you think are henges .Not fantasy stuff ,reliable archaeological surveys etc .

E.P. Grondine wrote:Okay, an Oxbridge archeologist shows up at Cahokia."I'm looking for the henge.""Its right here." (points to site map)...

No archaeologist , oxbridge or otherwise , who knew the terminology , would be looking for a henge at Cahokia. You might expect that they would be aware of the Wittry misunderstanding of "Woodhenge " and the subsequent archaeoastronomical nonsense .But that was 50 years ago and we have moved on and appreciated the errors ,although for some ,that's clearly not the case .

tiompan. you are fighting a lost battle.Both "henge' and "woodhenge" are in common use as neo-logisms.Easy to remember and use. and pretty generally used by north american archaeologists.That being the caseyour behavior now is similar to Springhead's.See the chart on that thread.

Usually people believe what they want to believe until reality intrudes.

circumspice wrote:But I somehow can't grasp why you would archive your NEO/Impacter stuff here, on this board. It is almost not even tangentially relevant to the subject of archaeology. We have more or less agreed that impacts may have entered into the archaeological record through ancient folklore & oral histories... But do you have to bore the shit out of us with your cockeyed theories? SHEESH!!! Give it a rest, will ya?

Agree ,although folklore/oral histories / ethnography have their limited uses in archaeology , large amounts of salt are required .E.P. The petty nonsense is your inability to face up to your errors .

tiompan, when I make mistakes I do my best to correct them immediately.IN this regard I'd also like to note that the wonderful thing about footnotesis that they allow you to blame your mistakes on someone else.

Since you have an issue with the American usage of the word "henge",I invite you to write as many nasty notes to the folks at Cahokia as your heart desires.

A henge is a roughly circular or oval-shaped flat area enclosed and delimited by a boundary earthwork - usually a ditch with an external bank.

The most distinctive components of any henge monuments are its bank and ditch. Most henges have either a single ditch or a pair of concentric ditches surrounding the central area.

This is not always the case, however, with some henges having no ditch while others have three.

The soil and bedrock taken from the ditch was used to build the henge bank which generally lay outside the ditch. The sizes of the banks varied proportionally with the size of the ditches. Typically, however, they seem to have been fairly broad at the base, five metres to 30 metres wide and up to five metres high.

Access to the central area was via formal entrances through the earthwork. Most henges have either one entrance or two opposed entrances.

The alignment of henges seen in the position of their entrances is highly variable and may have been as much conditioned by local geography as by any preferred orientation. There is, however, a slight tendency for henges with a single entrance to have that entrance set in the north or north-east sector while sites with two entrances are aligned SE-SSE to NW-NNW or ENE-E to WSW-W.

The original purpose and function of henge monuments is not fully understood. Because of the arrangement of banks and ditches it is generally accepted that they are ceremonial or ritual monuments.

Henges are generally classified into four main types according to the number of entrances and ditches they have. The traditional classification is as follows:

Class I Single entrance, single bank, and, usually, a single ditch circuit.Class IA Single entrance, single bank, and double circuit of ditches.Class II Two opposed entrances, single bank, and single ditch circuit.Class IIA Two opposed entrances, single bank, and two or more circuits of ditches.Class III Four opposed entrances, single bank, and single ditch circuit.

E.P. ,As everyone who has read this thread knows , you lost the battle a long time ago .Neither henge and woodhenge are neo logisms .It has been explained multiples times where you get it wrong .You are embarrassing yourself everytime you open your mouth .

Here is yet another description https://content.historicengland.org.uk/ ... rcles.pdf/."Henges (or henge monuments) are enclosures where, unlike those with a defensive purpose, the ditch lies inside the bank (although this is not the case at early sites like Stonehenge I – even though it gives its name to the type! – or Llandegai A). Some of them enclosed circles of upright timbers or stones, though most such circles are not associated with henge earthworks."Note that this is from Historic England , do check their credentials . You have still avoided any further mention of your nonsensical comment related to Thom ."by the way, the Thom's hypothesis about the henges is now established doctrine". Note what they have to say about him "a new interest in the astronomical alignments of stone circles, which was revived in the 1950s through the influential, if now largely discredited, work of Alexander Thom."Also note no mention of any hypothesis of his related to henges . You are living in an uncritical ignorant world view from the 1960's and 70s . We have moved on from Wittry and Thom , they have some excuse ,you don't .

(OBA approaches desk)LOL: Hello. Can I help you?OBA: Good afternnon. Well yes, I'm looking for the henge.LOL (grabs map/pampholet and unfolds it on desk and points):Do you see the mound there?its right down the street.(OBA looks at map)LOL: You just go out of the road into here,take a left and go on down the road. It's on the right.OBA: I've already driven by there. I did not see a henge there.LOL: It is on the north side of the road....Hold on(LOL walks around desk and points out window)Do you see that post down there?(OBA moves over, looks out window)OBA: Yes.LOL: Well, all the other posts are there as well.OBA: Ah, I see.. the wood ring.LOL: Yes. All of those posts are astronomically aligned.OBA: Yes; but where is the henge?LOL: Could you hold on for just a minute?(LOL returns around desk)(sotto voce) David, you you help me with this gentleman out there?He seems a little confused.(Dave leaves desk to speak with OBA)Dave: How can I be of help?OBA: Look, you seem to be confused. You are claiming that that wood ring is a henge.Dave: Why yes. All of those posts are in astronomical alignment.OBA: Don't any of you people know what a henge is?Dave: its been called the henge since it was first discovered, and all of the time I've worked here.OBA: That is no henge. Its a wood ring.Dave: Our archaeologist will be back this afternoon. Why don't you come back and talk about it with him?

[later that afternoon](OBA enters carryinrg large foot thick book.)Dave: I see you have returned. I'll go get our archaeologist.(Dave leaves, returns with archaeologist)Arky: How may I help you?OBA: You're claiming that that wood ring down there (points) is a henge.Arky: Yes. All of its posts are astronomically aligned.OBA: Don't any of you people know what a henge is?(slams large book on information Desk, and opens it up.)A henge is a roughly circular or oval-shaped flat area enclosed and delimited by a boundary earthwork - usually a ditch with an external bank.Where is the henge there?Arky: Well, we excavated it but have no had funds enough to rebuild it.OBA: I see. But isn't it a bit decptive to advertise it as a henge then?Arky: Well, someday we hope to get the money to restore it, and there's no point in having to re-do the pamphlets then.OBA: Oh. I see....OBA picks up book, leaves.Arky (sotto voce to LOL and Dave): Twit.